Peroxiredoxin AhpC1 protects Pseudomonas aeruginosa against the inflammatory oxidative burst and confers virulence

Author(s)

Rocha, Leonardo Silva ^[1] ; da Silva, Beatriz Pereira ^[2] ; Correia, Thiago M. L. ^[3] ; da Silva, Railmara Pereira ^[2] ; Meireles, Diogo de Abreu ^[4] ; Pereira, Rafael ^{[1, 3, 5]} ; Soares Netto, Luis Eduardo ^[4] ; Meotti, Flavia Carla ^[2] ; Queiroz, Raphael Ferreira ^{[1, 6]}

Affiliation

^[1] Univ Estadual Sudoeste Bahia, Programa Multicentr Posgrad Bioquim & Biol Mol, Vitoria Da Conquista, BA - Brazil

^[2] Univ Sao Paulo, Inst Quim, Dept Bioquim, Av Prof Lineu Prestes 748, Off 1001, BR-05508000 Sao Paulo, SP - Brazil

^[3] Univ Fed Bahia, Inst Multidisciplinar Saude, Programa Multicentr Posgrad Multicentr Ciencias F, Salvador, BA - Brazil

^[4] Univ Sao Paulo, Inst Biociencias, Dept Genet & Biol Evolut, Sao Paulo, SP - Brazil

^[5] Univ Estadual Sudoeste Bahia, Dept Ciencias Biol, Vitoria Da Conquista, BA - Brazil

^[6] Univ Estadual Sudoeste Bahia, Dept Ciencias Nat, Estr Bem Querer, Km 04 S-N, BR-45031900 Vitoria Da Conquista, BA - Brazil

• Document type: Journal article
• Source: REDOX BIOLOGY; v. 46, OCT 2021.
• Web of Science Citations: 0

Abstract

Pseudomonas aeruginosa is an opportunistic bacterium in patients with cystic fibrosis and hospital acquired infections. It presents a plethora of virulence factors and antioxidant enzymes that help to subvert the immune system. In this study, we identified the 2-Cys peroxiredoxin, alkyl-hydroperoxide reductase C1 (AhpC1), as a relevant scavenger of oxidants generated during inflammatory oxidative burst and a mechanism of P. aeruginosa (PA14) escaping from killing. Deletion of AhpC1 led to a higher sensitivity to hypochlorous acid (HOCl, IC50 3.2 +/- 0.3 versus 19.1 +/- 0.2 mu M), hydrogen peroxide (IC50 91.2 +/- 0.3 versus 496.5 +/- 6.4 mu M) and the organic peroxide urate hydroperoxide. Delta ahpC1 strain was more sensitive to the killing by isolated neutrophils and less virulent in a mice model of infection. All mice intranasally instilled with Delta ahpC1 survived as long as they were monitored (15 days), whereas 100% wild-type and Delta ahpC1 complemented with ahpC1 gene (Delta ahpC1 attB:ahpC1) died within 3 days. A significantly lower number of colonies was detected in the lung and spleen of Delta ahpC1-infected mice. Total leucocytes, neutrophils, myeloperoxidase activity, pro-inflammatory cytokines, nitrite production and lipid peroxidation were much lower in lungs or bronchoalveolar liquid of mice infected with Delta ahpC1. Purified AhpC neutralized the inflammatory organic peroxide, urate hydroperoxide, at a rate constant of 2.3 +/- 0.1 x 10(6) M(-1)s(-1), and only the Delta ahpC1 strain was sensitive to this oxidant. Incubation of neutrophils with uric acid, the urate hydroperoxide precursor, impaired neutrophil killing of wild-type but improved the killing of Delta ahpC1. Hyperuricemic mice presented higher levels of serum cytokines and succumbed much faster to PA14 infection when compared to normouricemic mice. In summary, Delta ahpC1 PA14 presented a lower virulence, which was attributed to a poorer ability to neutralize the oxidants generated by inflammatory oxidative burst, leading to a more efficient killing by the host. The enzyme is particularly relevant in detoxifying the newly reported inflammatory organic peroxide, urate hydroperoxide. (AU)

• FAPESP's process: 15/21563-9 - Study of the paper uric acid and redox modulation on the system cell innate immune microbicide activity
• Grantee: Railmara Pereira da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 13/07937-8 - Redoxome - Redox Processes in Biomedicine
• Grantee: Ohara Augusto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 15/10411-3 - Multi-User Equipment, previously approved in grant 2015/08166-5: stopped-flow
• Grantee: Iolanda Midea Cuccovia
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 18/14898-2 - Investigations of the redox processes in inflammatory response and associated pathologies
• Grantee: Flavia Carla Meotti
• Support Opportunities: Research Grants - Young Investigators Grants - Phase 2
• FAPESP's process: 19/26473-9 - The role of urate hydroperoxide in macrophage polarization
• Grantee: Beatriz Pereira da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)